I have an 88 Buick Regal. Here's the thing when I start her up, she runs like sh*t for approx. 8 seconds, the check engine light will come on, and she then purrs like a kitten. I retracted codes 33 and 34 MAP sensor voltage too high and MAP sensor voltage too low. And I also got a code for MAF sensor. I replaced both sensors (OEM), done voltage reference tests, assessed ground wires connections utilizing schematics. The check engine light still comes on revealing the same codes and this has now become a 2 month project. Can anyone help me? My baby's sick! graemlins/shield.gif

KB,
In a nutshell...the codes do not tell you that the sensor is bad. They only tell you that the sensor is sending an incorrect signal for the conditions to the ECM.
For instance, the MAP sensor voltage could be wrong because of a vacuum leak. You need to get a factory service manual so that you can understand the theory behind the operation of each sensor, then you can begin troubleshooting to find the real problem.
This is why I tell most do it yourselfer's that it would probably cost you less money in the long run to pay a good shop to find the real problem and fix it the first time. Dont get me wrong, I dont have a problem with anyone trying to fix thier own vehicle, I have been doing it for over 30 years now but....you have to be willing to invest in the equipment and information/training to be able to do it on modern vehicles. I normally dont work on cars (Machine shop only) but I try to fix my own. I just shelled out $1500 to buy a scanner and the factory manuals so that I can try to figure out an intermittant driveabilty problem on my Tahoe. Thats what it takes now days. For most people, that kind of money would be better spent paying a good shop to fix it for you.
Good luck fixing it,